Just as an arbitrary exercise, I thought I'd compile an alphabetical list thus:
The greatest philosopher whose name began with A was/is ... etc.
All choices are arbitrary. Obviously this is NOT a list of the 26th greatest thinkers, and if I drew up such a list a one-per-letter result would be a very odd coincidence.
Here, then, is what I came up with.
Averroes (portrayed above);
[Mary Baker] Eddy;
Isaac Israeli the Elder;
[William Butler] Yeats;
Zeno of Elea.
Yes, I've rather deliberately snubbed some big traditional names. Neither Plato nor Aristotle, neither Marx nor Hegel, neither Hobbes nor Locke. Marxists might be mollified a mite by my use of the letter L; advocates of the centrality of the classical Greek figures will appreciate the letter S; those of the empirical Brits might turn to M or O.
Within my beloved pragmatist tradition, I've had to make due without Peirce or Dewey. Dewey has a surrogate of a sort in Uznadze, the most important educational theorist of Soviet history. But I couldn't see "D" standing for anyone other than Descartes.
To include anyone else there would be like putting Des Cart before des horse.